Piezoelectric crystal detectors will be developed as personal monitors which can be used to detect exposure to toxic compounds indoors, at work-place sites. Crystals will be coated with selective adsorbents for the pollutants to be assayed. Detection of ppb concentrations, either continuously or as a dosimeter, will be possible. Each detector, and adsorbent, will be evaluated with respect to sensitivity, accuracy, selectivity, simplicity of design, stability, reversibility, speed of response, limit of detection and linearity of response. As a result of research in Phase I the feasibility of the use of piezoelectric crystal detectors as both dosimeters and continuous monitoring devices to detect exposure to toxic agents will be demonstrated. These devices will be constructed and tested in Phase II, and their use demonstrated for a host of applications.